Bernstein was discussing the Trump administration’s announcement Monday that Yates had been “relieved” of her duties after she “betrayed the Department of Justice” over the Muslim travel ban. Though many observers connected Trump’s move with that of Richard Nixon’s famed “Saturday Night Massacre,” Bernstein, who knows a thing or two about Watergate, pointed out that the comparisons aren’t exactly on-point.

“There’s a big difference, because the Saturday Night Massacre was really about firing the Attorney General when Nixon was the target of an investigation and was actively obstructing justice,” Bernstein said, noting Trump is “within his rights” to fire Yates.

Still, the journalist added, it’s “not wise that he did.”

“The president and his presidency is in chaos,” Bernstein told Lemon. “And it’s apparent to all but his most serious defenders, and those who are his greatest defenders and advocates. But for Republicans on Capitol Hill who are doubting his ability—doubting his stability—under pressure, this is an extraordinary series of events.”

“What Trump has done here is obstructed American principles,” Bernstein argued. “He hasn’t obstructed justice, he’s obstructed the most basic of American principles of what we stand for as a country.”

Later in the segment, Bernstein told Lemon Trump’s “executive order and chaos resulted not because of an imminent national security threat, but a political statement.” The journalist said Trump, chief White House strategist Stephen Bannon and pending Attorney General Jeff Sessions crafted the order for political purpose “at the expense of our genuine national security and the expense of our genuine history and Democratic principles.”

“He’s undermining his own legitimacy …” Bernstein said. “He has undermined, in one week, his own legitimacy to the point where there are many Republicans on Capitol Hill who question his competence. That is the worst thing he could have in terms of his legitimacy.”